/*
 *  Axolotl - Alternate persistence for Grails
 *  Copyright (C) 2008  Juanjo García Latre
 *
 *  This library is free software; you can redistribute it and/or
 *  modify it under the terms of the GNU Lesser General Public
 *  License as published by the Free Software Foundation; either
 *  version 2.1 of the License, or (at your option) any later version.
 *
 *  This library is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 *  Lesser General Public License for more details.
 *
 *  You should have received a copy of the GNU Lesser General Public
 *  License along with this library; if not, write to the Free Software
 *  Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
 */
package com.googlecode.axolotl.query;

import java.io.Serializable;

import com.googlecode.axolotl.query.groovy.QuerySerializer;


/**
 *
 * @author     juanjo
 */
public abstract class Criterion implements Serializable, Cloneable {
	
	public static final QueryVisitor<CharSequence> STRING_RENDERER = new QuerySerializer();

	private boolean negated = false;


	/**
	 *
	 */
	public Object clone() {
		try	{
			return super.clone();
		}
		catch (CloneNotSupportedException exc) {
			return null;
		}
	}


	/**
	 *
	 */
	public boolean isNegated() {
		return negated;
	}


	/**
	 * 
	 */
	public void setNegated(boolean negated) {
		this.negated = negated;
	}


	/**
	 * Equivalent to <code>setNegated(true)</code> but returns this <code>Criterion</code>.
	 */
	public Criterion setNot() {
		negated = true;
		return this;
	}


	/**
	 * Creates a negative clone.
	 */
	public Criterion cloneNegated() {
		return ((Criterion) this.clone()).setNot();
	}


	/**
	 * 
	 */
	public abstract <T> T accept(QueryVisitor<T> visitor);


	/**
	 *
	 */
	public String toString() {
		return accept(STRING_RENDERER).toString();
	}


	/**
	 * @see java.lang.Object#hashCode()
	 */
	public int hashCode() {
		return toString().hashCode();
	}

}
